This paper presents an ultra-low power CMOS voltage reference circuit robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of [-40, 200°C] and for different process corners. Robustness to radiation was simulated using a custom model parameters using TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e. 1 Mrad (Si) performed at three different temperatures (room temperature, 100°C and 200°C). The maximum drift of the reference voltage VREF depends on considered temperature and on radiation dose, however it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage, is about 20 µW at room temperature and only 75 µW at a high temperature of 200°C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the SOI MOSFETs were extracted under different conditions. The evolution of VREF and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The toal occupied area including pad-ring is less than 0.09 mm².